FIG. 1 shows a schematic view of a portion of a prior art grinding machine. In FIG. 1 a pivotable tool spindle 120 can be seen in a horizontal position. The tool spindle 120 here comprises a spindle housing 121 and a spindle motor, which is hidden in the interior. Attached to the tool spindle 120 is a grinding worm 20, which can be rotatably driven about a tool spindle axis B by means of the spindle motor. In order to enable the pivoting of the tool spindle 120, a pivot axis A is provided, which in this case stands perpendicularly to the drawing plane. Such a grinding machine, which is equipped with a pivotable tool spindle 120, typically comprises a pivot plate, indicated by a dashed circle K in FIG. 1. The pivot plate can be rotated about the pivot axis A in the drawing plane. The pivot axis A is located at the center of the circle K. The pivotable tool spindle 120 is arranged, for example, on a machine stand 101, which can be seen in outlines in the background of FIG. 1.
The workpiece to be ground is not shown in FIG. 1, but the position of the vertically extending workpiece spindle axis C is shown, which intersects with the pivot axis A in the prior art, i.e. in FIG. 1. The workpiece typically sits on a workpiece spindle (not shown), which can be rotationally driven around the workpiece spindle axis C.
In order to intercept unequal torques which act on the tool spindle 120 in this known configuration, the pivot plate, or the pivot axis A, can be mechanically clamped during the grinding of the workpiece. In this case, the pivot axis A can be used only as a setting axis. This means that the pivot axis A cannot be used dynamically, but only statically.
If one wishes to use the pivot axis A as a moving axis during grinding, mechanical clamping is not useful. In this case, a drive motor is required which keeps the pivot axis A in position and can also move it dynamically. The size of the drive motor depends on the torque to be applied. This temporary retaining can be effected, for example, in such a way that the drive motor, which serves to pivot the pivot plate, predetermines a correspondingly large holding current. However, the predetermination of a holding current increases the power consumption of the grinding machine.